A graphics processing unit (GPU) may be described as a microprocessor designed to render graphical images efficiently for display, speeding up the rendering process and relieving the central processing unit (CPU) of this task. A computer system having a GPU as well as a CPU can be expected to render graphical images faster than a computer system without a GPU and to be more efficient in performing other computational tasks because the CPU is not being burdened with rendering graphical images. In a multi-color image handed to a GPU for rendering, color shading is described by a color gradient which includes two parameters: a color shade, and a distance in number of pixels for which that shade is to be displayed.